Magnetic plate attachment for planographic presses



Dec. 19, 1933. J. 5. FLEMING 1,939,681

MAGNETIC PLATE ATTACHMENT FOR PLANOGRAPHIC PRESSES Filed Sept. 22. 1927 INVENTOR ATTORNEYS.

Patented Dec. 19, 1933 UNITED STATES MAGNETIC PLATE ATTACHMENT FOB PLANOGRAPHIC PRESSES John Stuart Fleming, Toronto,

assignor, by mesne Fold, Inc., Niagara F of New York Ontario, Canada, assignments, to Niagara ails, N. Y., a corporation lication September 22,1921 Serial'No. 221,183.

10 Claim.

This invention relates to improvements in planographic or similar printing machines, and with reference to some of its more particular features, it relates to an improved form and method of attaching planographic and similar printing plates in operative position upon a rotary printing cylinder or like support.

It is a general object of the invention to provide a simple and improved means for securing a planographic or like printing plate in operative position upon a rotary printing cylinder or like support for use in a printing machine.

A further object is to provide an improved securing means for printing plates of the class mentioned whereby the planographic or other printing plate may be quickly and easily placed and secured in operative position, and which is simple in construction, whereby cumbersome, expensive, unreliable, and otherwise unsatisfactory plate securing devices of prior practice are entirely avoided.

A further object is to provide an improved securing device for plates of the class mentioned, whereby the planographic or similar printing plate is effectively secured in position upon its supporting cylinder in a printing machine by magnetic means.

A further object is to provide an improved el'ectro-magnetic attaching device for planographic, or similar printing plates, whereby planographic plates magnetically supported upon a cylinder may be selectively released.

Other objects will be in part pointed out in connection with the following detailed description of an illustrative but preferred embodiment of; the invention, and will be in part obvious in connection with said description.

The invention. accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplifled in the construction hereinafter set forth and the scope of the application of'which will be indicated in the claims.

For a more complete understanding of the nature and objects of the invention, reference is had to the accompanying detailed description and to the drawing, in which, I

Fig. 1 is a fragmentary perspective partially diagrammatic view exemplifying the invention in connection with a rotary cylinder such as may be utilized in planographic printing apparatus,

Fig. 2 is a detail transverse section through the cylinder, and

Fig. 3 is a view similar to Fig. 2 of a modification.

graphic or similar printing plates are supported and detachably secured. It will be understood, however, that the invention is not limited in its application to this type of machine.

In the embodiment shown, a rotary'drum or cylinder 5 is mounted by means of a supporting shaft 6 in suitable hearings in a planographic printing machine of any preferred known construction, a detailed disclosure of which is unnecessary to a complete understanding of the invention, and of its field of application. A plurality of flexible planographic printing plates 7 are arranged in a circumferential series and supported upon the cylindrical surface of the cylinder 5 with the printing surfaces thereof faced outwardly so they may be brought into contact with the print paper or other material as the cylinder is rotated. These planographic plates 7, for convenience, are shown in the drawing as being somewhat exaggerated in thickness, but it will be understood by those skilled in the art that these plates may be of form ordinarily employed in planographic printing processes, and that they are quite thin and very flexible so as to readily adapt themselves to the contour of the supporting surface and to lie in intimate supporting engagement therewith. Since it is important that the plates may be maintained in correctly aligned position throughout the printing operation, and it is frequently necessary to change or replace the plates it is important that the plate attaching device be of such a nature as to firmly hold the plates in position, but that it be readily releasable to permit removal thereof.

As many separate planoraphic plates 7 as desired, may be employed and for the purpose of independently supporting these plates the periphery of the supportingcylinder may be divided into circumferential sections 8, supported upon the shaft 6 in any desired manner, as by means. of the spiders 9, to which the cylindrical sections 8 may be attached. Each of the cylindrical sections 8 in the embodiment shown provides an individual support for one of the planographic plates and is preferably coextensive with or may be smaller or larger in extent than the prepared area of the planographic plate. The supporting sections 8 may be formed by providing axially disposed longitudinal grooves in the cylindrical surface, or they may be formed in sepa- The cylindrical sections or supporting plates- 8 are of magnetic material such as iron or' steel,

and are magnetized so as to holdthe planographic plates in operative position by magnetic attraction. The supporting spiders 9 are preferably made of non-magnetic material such as bronze or brass. The supporting plates 8 may be of hard steel and permanently magnetized, but they preferably form magnetic pole pieces of electro-magnets of which the integral inwardly disposed extensions 11 form the cores. Only a single core is shown for each pole piece or cylindrical section 8, but it will be understood that additional cores may be provided if desired, the cores being arranged so that the entire area of each pole piece is .strongly magnetized. throughout its extent, thereby to attract the planographic plate at all parts thereof so as to hold it effectively in operative position. It will be understood that the planographic plates themselves are made of a magnetic metal, or include such a metal in their composition, so as to be attracted by the magnetized pole pieces 8. ,In this connection it is important to note that the flexible planographic plate '7 is itself of magnetic material so as to be attracted by the magnetic pole pieces, thus providing the plate-attaching magnetic attraction. Thus, the flexible plate, as shown, may be of a single integral thickness of magnetic material. This provides a very simple structure affording a practical attaching arrangement for flexible printing plates and avoiding complex and inexpensive construction such as would be the case if the magnetic attractive material were in the form of a separate part or parts with some manner of attaching means for attaching them to the flexible planographic plate proper.

In order to assist in holding and steadying' the planographic plates in operative position upon the supporting pole pieces, each plate is preferably provided with one or a plurality of dowel pins or lugs 12 which may be integral with the plates or soldered or brazed thereon. These lugs are respectively positioned so as to register with seats or apertures 13 formed in the outer faces of the supporting plates or pole pieces, and when thus assembled and held by magnetic attraction in operative position, the planographic plates are steadied and supported against edgewise movement or vibration. By this means the planegraphic plates are accurately initially positioned and aligned and are maintained in such position throughout the various printing operations.

For the purpose of energizing the cylindrical supporting sections or pole pieces 8, coils 14 surround the cores l1 and are connected to receive electric energy from a source E through conductors 15, leading through slip rings 16 mounted upon. and insulated from the shaft 6, and through contact brushes 1'! to one terminal of the source E. The return conductor 18 leads through a similar slip ring 19 and brush 20 to the opposite terminal of the source A control switch 21 is provided with a plurality of contacts 22 each connected through conductors 23 to the source E, and may also be provided with movable contacts 24 to which the conductors 15 are respec-- magnetized or demagnetlzed.

When it is desired to place one of the pianographic plates in operative position upon one of the supporting plates or sections 8 of the supporting cylinder, said plate ispositioned with the dowel pins or lugs 12 aligned with the seats 13, and the corresponding control switch 24 is closed, thus magnetizing the supporting pole piece 8 and magnetically attracting the planographic plate to secure it in correct operative position upon the supporting cylinder. Similarly, when it is desired to remove one of the planograp'hic'plates the corresponding control switch 24 will be opened, thus de-energizing the plate supporting section 8, whereupon the plate 'I will be released and can then be lifted from its position upon the cylinder. In case the supporting sections 8 are permanently magnetized, it will be necessary to forcibly lift the planographic plates from supported position against the magnetic attracting force, when it is desired to remove said plate.

According to the embodiment of Fig. 3 the forward edge of the planographic plate 7a is provided with an attachment for attaching it to the cylinder 5a, and if desired the rearward edge of the plate may be also attached to the cylinder. It will be observed that the cylinder rotates in the direction indicated by the arrow in Fig. 3, so that the attachment 25 is positioned at the leading edge of the plate, or that edge first contacting with the paper during a printing operation.

The attachment 25 is shown as being formed by bending the edge of the thin flexible plate 12a backwardly. or reversely upon itself to form the hooked or reversely disposed flange 26 which is snugly received within a slot 2'? formed in the cylinder at the gap 10a as shown. This slot extends longitudinally of the cylinder forming in effect a retaining or supporting nose 28 fltting into the channeled edge of the plate formed by the flange 26. This attachment provides an effective auxiliary means for retaining the edge of the plate in close even contact with the cylinder surface. The rearward edge of plate In may be inwardly turned and secured by engagement with the surface of gap 10a or otherwise. It will be noted that the rear retaining flange or lug is disposed on the plate at an angle greater than an acute angle, thus providing for retaining the planographic plate "(a securely in position with the cooperation of the magnetic holding device, but permitting said plate to be lifted outwardly at its rear endfrom engaged position. This arrangement also provides a simple and practical means for placing the plate in its operative position.

Such an attachment as that described in connection with Fig. 3 may be used at the rearward or following edge of plate 70. instead of being placed at the forward edge thereof. Also with the forward attachment for the planographic plate as described, the rearward edge may be inwardly turned around the adjacent shoulder formed by the gap 10a in the cylinder surface, as shown in Fig. 3. The engagement of this inwardly turned rearward flange or supporting lug with the shoulder assists in retaining the rearward edge of the planographic plate in position. An additional securing means having a more positive engagement with the rearward inwardly disposed flange, and providing a more positive attachment than that shown, may be provided if desired.

Since certain changes may be made in the above construction, and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description, or shown in the accompanying drawing shall be interpreted as illustrative. and not in a limiting sense.

It is also to be understod that the following claims are intended tocover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a printing device, in combination, a plate cylinder having a plurality of peripheral sections providing seats for receiving flexible planographic printing plates in operative position thereon, a magnetizing coil for each of said peripheral sections for magnetizing the same, and means for selectively energizing or de-energizing said coils.

2. In a printing device, in combination, a flexible planographic plate of magnetic material, said flexible. magnetic plate itself having a marginal portion thereof offset to form a marginal supporting lug, said marginal portion being turned backwardly upon the plate to form a chanelled attaching edge, a supporting bed for said plate, and magnetic means cooperating with said magnetic plate for retaining it in operative position ing bed. I

4.'A planographic plate of single integral thickness and of magnetic material and being thin and of sufliciently marked flexibility to readily flex or bend from its plane to conform to a cylindrical supporting bed, said plate having its opposite marginal portions inwardly offset to form opposed forward and rearward marginal supporting lugs, the forward of said supporting lugs being rearwardly turned to form a hooked retaining lug, while the rearward supporting lug is disposedat an angle with the plate larger than an acute angle. I

5. In a printing device, in combination, a rotary plate cylinder having a cylindrical, magnetic, plate supporting bed, and a planographic plate of a single integral thickness of magnetic material supported upon said supporting bed and in contact therewith, said planographic plate being thin and of sufficient flexibility to readily flex or bend from a plane to conform to said cylindrical bed and having thereon protruding from its inner surface a plurality of spaced steadying lugs integrally formed upon said plate and engaging said cylinder to steady the plate in operative position.

6. In a printing device, in combination, a rotary plate cylinder having a cylindrical, magnetic, plate supporting bed, and a planographic plate of a single integral thickness of magnetic material supported upon said supporting bed and in contact therewith, said planographic plate being thin and of sumcient flexibility to readily flex or bend from a plane to conform to said cylindrical bed and having thereon protruding from its inner surface a plurality of spaced steadying lugs integrally formed upon said plate and engaging said cylinder to steady the plate in operative position, said planographic plate being substantially continuously overlapped throughout its active printing extent by said magnetic supporting bed.

7. In a printing device, in combination, a rotary plate cylinder having a cylindrical, magnetic, plate supporting bed, and a planographic plate of a single integral thickness of magnetic material supported upon said supporting bed and in contact therewith, said planographic plate being thin and of sufficient flexibility to readily flex or bend from a plane to conform to said cylindrical bed and having thereon protruding from its inner surface a plurality of spaced steadylng lugs integrally'formed upon said plate and engaging said cylinder to steady the plate in operative position, circumferentially spaced forward and rearward fixed plate retaining seats on said bed, and said steadying lugs including forward and rearward inwardly turned marginal flanges, one of which has a hooked attaching part engaging one of said fixed retaining seats.

8. In a printing device, in combination, a magnetic plate supporting bed, a planographic plate of magnetic material in contact with said bed and magnetically supported thereby, fixed plate retaining seats spaced apart on said bed, one of which includes a reversely disposed slot, and plate retaining lugs on said plate in retaining engagement with the respective fixed seats, one of said retaining lugs having a hooked formation engaging in said reversely disposed slot.

9. In a printing device, in combination, a plate supporting bed having a series ofsections, each forming a plate supporting seat, a separate flexible planographic plate supported on each supporting seat, inter-engaging lugs between each of said supporting seats and the planographic plate thereon for steadying the latter in operative position, a magnetizing coil for each of said bed sections, and means. for selectively energizing and deenergizing said coils.

10. In a printing device, in combination, a plate cylinder having a plurality of peripheral sections providing a plurality of magnetic plate supporting beds, each having a cylindrical sup.-

porting surface, a planographic plate of a single [integral thickness of magnetic material supported upon each of said cylindrical supporting beds and in contact therewith, each of said planographic plates being thin and of suflicient flex ibility to readily flex or bend from a plane to conform to the cylindrical bed, and each plate having thereon protruding from its inner surface a plurality of spaced steadying lugs engaging the bed to steady the plate in operative position, a magnetizing coil for each of said supporting beds for magnetizing the same, and means for selectively energizing or deenergizing said coils.

J. STUART FLEMING. 

